1. Field of the Application
The present application relates to the housing of an axial turbomachine. More particularly, the present application relates to contiguous shells in the housing of an axial turbomachine. More particularly, the present application relates to fixing brackets between the shells in the housing of an axial turbomachine. The present application relates to the concentricity between two shells of a turbomachine fixed with radial flanges. The present application relates also to an axial turbomachine.
2. Description of Related Art
Turbomachines generally include a plurality of annular passages through which flows of air pass in order to generate a driving force. The airflow passes through a fan, a compressor, a combustion chamber, and turbines. In or between these elements, the housing of the turbomachine helps to guide the flow by constraining it within the turbomachine itself.
The housing is made up of annular walls mirroring the changes in section of the stream. To this end, it comprises shells having a generally tubular shape arranged along the engine's axis of rotation. The shells have functional surfaces in contact with the stream. They can form internal and/or external surfaces that physically define the stream. The shells may be cylinders or parts of cylinders. Where they join roughly forms a cylinder or the base of a cone of the desired length.
The functional surfaces of the shells must match as closely as possible the theoretical geometry of the airstream, in particular its continuity. This results in the requirement that the various shells must follow a general concentricity, without which steps or discontinuities may occur in the stream. These defects lead to a reduction in the efficiency of the turbomachine. Uncontrolled modes of operation can occur.
Patent EP123645 A1 discloses an assembly of two adjacent shells with flanges connected by axial screws for fixing them. One of the shells has a female cylindrical surface inside which a male cylindrical surface on the other shell is located, so as to form a shaft-bore assembly. The male and female cylindrical surfaces are located at the bases of the flanges. This type of assembly makes it possible to optimise the position and orientation of the shells relative to one another. However, the screws require an unobstructed locating surface. This surface may be greater than the inherent size of the screws to improve the distribution of mechanical stresses. The superposition of the cylindrical bearing face and the locating surface for the screw member that the radius of the outer flange has to be increased. The radius between the flange and the cylindrical bearing surface further increases the outer radius of the flange. This flange size is cumbersome and increases the weight of the shell. Such a radial flange can be difficult to implement in a splitter nose with a given lift/drag ratio. The presence of equipment in the nose may make it impossible to assemble.
Patent EP2077183 B1 discloses a junction between two shells of a turbomachine positioned with respect to each other using their flanges. These are located at the axial ends of the shells. The radial ends of the flanges have male and female surfaces. This solution allows optimum positioning while avoiding any constraints imposed by locating surfaces for screws. However, it requires a cylindrical portion at the top of one of the flanges, thereby increasing the radius of the latter.
Although great strides have been made in the area of housings for turbomachines, many shortcomings remain.